1. Field of the Invention
The present invention relates to a vertical type semiconductor device producing apparatus, and more particularly, to a vertical type semiconductor device producing apparatus which alternately flows a plurality of kinds of gases contributing to film formation, and forms films on stacked substrates.
2. Description of the Related Art
FIG. 7 shows an atomic layer deposition apparatus (ALD apparatus, hereinafter) which is a conventional semiconductor device producing apparatus which alternatively flows a plurality of kinds of gases contributing to film formation, and forms films. In this apparatus, two kinds of process gases a and b which contribute to film formation are alternately supplied into a reaction chamber 1, the reaction chamber 1 is exhausted, the gases are adsorbed onto substrates in the reaction chamber 1 and reacted, thereby forming films on the substrates. In this case, a gas supply amount of the process gases a and b is determined by controlling the flow rate by mass flow controllers (MFC) 2 and 3 provided in gas supply tubes 7 and 8. A pressure in the reaction chamber 1 is determined by controlling an exhaust amount by adjusting opening of an exhaust valve 6 provided in the exhaust tube 9.
According to the conventional ALD apparatus, however, when process gas is supplied to the reaction chamber, since the process gas is supplied while controlling the exhaust amount from the reaction chamber, a gas pressure can not rise in a short time, and there is a defect that the adsorbing speed and reacting speed are slow due to the delay of the gas pressure rise. In the case of single substrate-feeding type ALD apparatus which simultaneously processes about one or two substrates, since a capacity of the reaction chamber is small, this defect is not so serious. In a case of a batch type vertical type ALD apparatus which simultaneously processes a large number of stacked substrates, however, since a capacity of the reaction chamber is large, delay in adsorbing and reacting speed appears remarkably, and there is a problem that throughput is largely deteriorated.
Japanese Patent Application Laid-open No. 9-82696 describes a single substrate-feeding type film forming apparatus which keeps flowing oxygen (O) radical into a reaction chamber, TEOS gas is intermittently supplied for about two seconds each, and cohesive films are formed. In this apparatus, a gas supply system in which gas is supplied from a TEOS cylinder to a reaction chamber is provided with gas reservoirs 303 and 304, TEOS gas reserved in the gas reservoirs is supplied to the reaction chamber. Since two gas reservoirs are provided, it is possible to reserve gas in one of the gas reservoirs while the other one is being used, and the throughput is enhanced. However, the apparatus provided with the gas reservoirs is of single substrate-feeding type in which a capacity of the reaction chamber is small, and the apparatus is not a vertical type apparatus having a large capacity of the reaction chamber. Further, the apparatus is not the ALD apparatus which alternately supplies process gas a and b into the reaction chamber.